The HCl in your stomach will activate sodium chlorite. The issue is that you have little control over that reaction. Too much chlorine dioxide can damage your stomach lining so be careful.
Chlorine dioxide is used to bleach teeth whiter. The problem is that when the concentration gets higher, it pits and damages the enamel on the teeth. Once again it all comes down to the concentration and PH of the solution.
A dose of Miracle-Mineral-Supplement activated and mixed with 4 ounces of water ends up with a PH of about 3 and the free chlorine dioxide concentration is variable depending upon the activation time. Over time a PH 3 solution will damage your teeth, so be sure to buffer the PH to something more neutral.